Abstract: To solve the instability problem in target detection of torpedo active acoustic homing, a quantitative facticity judgment method for target detection is put forward. In this method, according to the target parameters detected by a torpedo, such as the range and azimuth, inverse coordinate calculation is adopted to calculate target point in torpedo inner coordinate system, then the coordinate of the target point is transferred. The distance between detected target point and actual target point is calculated in the same rectangular coordinate system to judge the facticity of the target detected by torpedo active acoustic homing. This algorithm is implemented with the programming language Python, and two examples prove the feasibility of the proposed method